BTW. For anyone interested, here is a link to multiported avionics cooling fans for 14 or 28 volt.

http://www.edmo.com/s2/s2-18.asp

Almost all avionics today are fitted with cooling ports. A small hose <1" runs from the fan to the radio. this might solve heat problems in any install. I think all that would be necessary would be to blank off the bottom large hole in the mounting tray and have an adapter for hose made.